Vertically Spaced Die Attach Pads Preventing Air Voids

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Solution Overview

Problem

Integrated circuit packages face partial dielectric discharge failures due to air voids in the mold compound filling the gap between die attach pads, which existing designs fail to adequately address without increasing lateral spacing or changing die sizes.

Innovation Solution

The leadframe design features die attach pads positioned at different elevations with sloped or rounded edge surfaces, increasing the effective separation distance without altering the package footprint or die sizes, ensuring complete mold compound filling and preventing partial discharge failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If die attach pads are positioned closer together to maintain package footprint, then manufacturing efficiency is improved, but partial dielectric discharge failures occur due to air voids in mold compound

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoiddischarge failure prevention

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent transitions from lateral spacing to vertical spacing by positioning die attach pads at different elevations. The first die attach pad is at a first elevation and the second die attach pad is at a second elevation, creating vertical separation that prevents air void formation while maintaining close lateral proximity for manufacturing efficiency

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent changes the spatial parameter from horizontal distance to vertical distance between die attach pads. By positioning pads at different elevations with sloped or rounded edge surfaces, the effective separation distance is increased in the vertical dimension while lateral footprint remains compact

Inventive Principle:

Principle #35Parameter changes

2Reliability

If lateral spacing between die attach pads is increased to prevent discharge failures, then reliability is improved, but package footprint increases

Engineering Contradiction:

Improvedischarge failure preventionVSAvoidpackage footprint

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent resolves the footprint issue by moving the separation dimension from lateral to vertical. Die attach pads are positioned at different elevations rather than being laterally spaced, which prevents discharge failures without increasing the horizontal package footprint

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Productivity

If die sizes are reduced to accommodate closer pad spacing, then manufacturing efficiency is improved, but electrical performance deteriorates

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidelectrical performance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent enables close lateral pad spacing with full-sized dies by introducing vertical separation. The different elevations and sloped/rounded edge surfaces prevent air void formation, allowing large dies to be positioned close together laterally without compromising electrical performance or manufacturing efficiency

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS11342247B2Leadframe with vertically spaced die attach pads

Publication Date: 2022.05.24 TEXAS INSTRUMENTS INC

AI summary

A leadframe includes a first die attach pad (“DAP”) having a first longitudinally extending edge surface and a second DAP having a first longitudinally extending edge surface. The second DAP is positioned with the first longitudinally extending edge surface thereof in adjacent, laterally and vertically spaced relationship with the first longitudinally extending edge surface of the first DAP.